Fault lines and contrasting landscapes

Question 1

Introduction..
Tectonic = seismic = fault lines.
Stress = earthquakes and uplift along reverse or thrust faults
Distinctive mountainous landscapes = Moine Thrust
Pull apart = tension = downward movement along normal faults
Creates rift valleys & depressions = Lake Baikal in Russia
Horizonal movement = along strike slip = San Andreas

Answer 1

Tectonic processes can produce a variety of landscapes that are formed by seismic processes creating fault lines. Tectonic processes can compress the crust creating stress that leads to earthquakes and uplift along reverse faults or thrust faults.
This leads to distinctive upland landscapes (e.g the mountainous landscape of NW Scotland created by the Moine thrust).
However tectonic processes can also pull the crust apart and this causes tension, leading to earthquakes and downward movement along normal faults.
This can create rift valleys and other depressions in the Earth’s surface (e.g. Lake Baikal in Russia).
Tectonic processes can also create horizontal movement along strike-slip faults (e.g. the San Andreas fault in California).

Question 2

The different tectonic processes create different types of fault movement and this results in different landscapes…

Answer 2

The different tectonic processes create different types of fault movement and this results in different landscapes. This is illustrated clearly by comparing the processes that created the Great glen fault in Scotland and the East African Rift System and their resulting landscapes.

Question 3

The Great glen fault

Answer 3

The Great glen fault dissects Scotland in a roughly SW-NE direction.
It runs from Fort William in the south to the Moray Firth in the north.
The fault was caused by horizontal movement and is a strike-slip fault (BGS website).
It has created a line of weakness that has been subsequently eroded by glaciers to create a distinctive landscape of a long valley with several lakes, including Loch Ness.

Question 4

East African Rift Valley

Answer 4

The East African Rift System is a much larger landscape and is the product of the ongoing creation of a divergent plate boundary.
Underneath the East African Rift System the crust is being pulled apart by convection currents in the mantle. This creates tension and a series of normal faults have been formed where the crust has moved downwards and apart. The resulting landscape is a huge rift valley that consists of two broadly parallel rifts that extend for over 4000km from the Red Sea to Mozambique, with the fault scarps reaching heights of 600m (A2 Edexcel Geography).
The areas of crust that have dropped are known as graben, with the central block of the rift valley being called a horst.
This case study illustrates how the nature of the plate movement at plate boundaries can create distinctive landscapes..

Question 5

Thus it can be seen that the tectonic processes producing strike slip faults can produce one type of landscape and the processes that produce normal faults produce distinctively different landscapes…

Answer 5

Thus it can be seen that the tectonic processes producing strike slip faults can produce one type of landscape and the processes that produce normal faults produce distinctively different landscapes.
Although in these examples both resulted in valleys, Great Glen is a valley that has been eroded along the fault line as it was a line of weakness whereas the East African rift valley is a much wider and longer valley with horst and graben.
It can also be seen that the direction of plate movement at plate boundaries also leads to distinctive landscapes. Divergent movement lead to the formation of a rift valley and this is distinct from the mountain ranges created by convergent movement.

Question 6

Folds

Answer 6

Folds
Folds are the result of compression. Folds can go upwards to produce an anticline and downward to produce a syncline. What the actual landscape looks like are a result of smaller scale, processes that happen afterwards i.e (action of erosion & weathering).
The Andes:
The Andes Mountains form one of the most distinctive landscapes on earth as they are one of the longest mountain ranges, stretching over 7,000 km along the west coast of South America. The height of the Andes is about 4,000 meters high, and it includes peaks above 6,000 meters. This landscape also contains the Atacama Trench which reaches a maximum depth of 8,065 metres below sea level. The mountains have been formed as a result of the convergence of the Nazca plate and the South American plate. The heavier oceanic crust of the Nazca plate is pushed towards the South American plate, and because it is denser is subducted underneath. The South American plate is less dense so sits on top of this subduction zone, but the rocks of the South American plate have been folded upwards and crumpled into fold mountains.